Method and system for well access to subterranean formations

ABSTRACT

The invention provides a method and system for accessing a well to subterranean formations in which a first well control assembly is directly associated with the well and a second well control assembly is remotely and capable of being in fluid communication with the well.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims the benefit of U.S. Provisional Patent Application 61/356,946, filed Jun. 21, 2010, entitled METHOD AND SYSTEM FOR WELL ACCESS TO SUBTERRANEAN FORMATIONS, and also claims the benefit of PCT/US2010/050534, filed on Sep. 28, 2010 entitled “System and Method For Drilling A Well That Extends For A Large Horizontal Distance”, and also claims the benefit of U.S. Provisional Application No. 61/334,333, filed on May 13, 2010 entitled “System And Method For Drilling A Well That Extends For A Large Horizontal Distance”, the entirety of each is incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a method and system for design, construction, and operation of one or more wells in a subterranean formation. More specifically, the method and system provide multi-entry access to wells.

BACKGROUND

The traditional method of well architecture consists of a single point-of-entry (“mono-entry” wells), either into or out of the well at surface, which has been the primary basis of all wells since the origin of the modern day oil & gas industry by Edwin Drake at Titusville, Pa. in 1859.

A mono-entry well has a single point-of-entry to drill, complete, produce, service, and log data to or from subterranean formations. In typical oilfield operations, the traditional activities include: 1) drilling a borehole, 2) running and grouting casing in the borehole with cement, 3) deepening the well by drilling through the previously grouted casing, 4) repeating this process until reaching the target depth, 5) completing the well to achieve hydraulic communication with the reservoir by any number of operational connecting procedures (such as perforating the last string of cemented casing with explosive charges), and 6) producing hydrocarbons to surface. Furthermore, the traditional method of well architecture generally affords that the well may be re-entered for: 1) servicing, to affect mechanical repairs, enhance production, or re-configure the well, and 2) logging, to obtain measurements or samples, to perform subsequent analysis and decision making.

Historically, a single point-of-entry also presumed a “single pathway” to drill, complete, produce, service and log within the well. Much later (circa 1990s), the industry advanced technology for well architectures to permit for “multiple pathways” below the surface (“multi-lateral” wells), while maintaining a single point-of-entry from the well surface.

In a related area, dual-, triple-, and quad “tubingless completions” have been proposed that share shallow casing strings, generally having a common wellhead and separate production trees, which have no connecting fluid pathways and therefore only a single point-of-entry from surface.

When control of a well has become lost accidentally during drilling or production, one method of regaining control of the well is to drill a relief well to intentionally intersect the well that is undergoing well control problems. Relief wells are drilled to intersect the blowing well at or very near the inflow source of hydrocarbons (i.e., reservoir interval) with the intention of “killing the well” with heavy-weight (i.e., high density) drilling fluids and cement. The first recorded success of relief well drilling occurred near Conroe, Tex. in 1933.

Improved systems and methods are needed to provide access to wells.

SUMMARY

The present invention provides a method and system for accessing a well to subterranean formations in which a first well control assembly is directly associated with the well and a second well control assembly is remotely and capable of being in fluid communication with the well.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features that are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is merely exemplary and provided for the purpose of illustration and description only, and is not intended as a definition of the limits of the present invention.

FIG. 1 schematically illustrates one embodiment of a well architecture that provides multi-entry access to a wellbore.

FIGS. 2A, 2B, 2C, 2D, 2E, 2F, 2G, 2H, 2I, 2J, and 2K schematically illustrate embodiments having the multi-entry access capability of FIG. 1, and optional well access capability to a primary wellbore through an intercepting juncture. FIGS. 2A through 2K illustrate non-limiting examples of intercept pathways.

FIG. 3 schematically illustrates another embodiment of a multi-access well system similar to FIG. 2B except that the primary wellbore is illustrated as having multi-lateral pathways.

FIG. 4 schematically illustrates another embodiment of a multi-access well system similar to FIG. 2B except that a well template provides support structure for three wells with well control assemblies for each.

It should be noted that the figures are merely exemplary of several embodiments of the present invention and no limitations on the scope of the present invention are intended thereby. Where considered appropriate, reference numbers may be repeated among the drawings to indicate corresponding or analogous elements. Further, the figures are merely exemplary and generally not drawn to scale, but are drafted for purposes of convenience and clarity in illustrating various aspects of the invention.

NOTATION AND NOMENCLATURE

Certain terms are used throughout the following descriptions and claims to refer to particular system components. This document does not intend to distinguish between components that differ in name but not function.

As used herein, the terms “well” or “wellbore” or “well segment” refer a hydraulic pathway originating at surface with access to subterranean formations. The terms are interchangeable when referring to an opening in the formation. A well may have a substantially circular cross section, or other cross-sectional shapes (for example, circles, ovals, squares, rectangles, triangles, slits, or other regular or irregular shapes). Wells may be cased, cased and cemented, open-hole, or partly cased and partly open-hole, and may be any type, including, but not limited to a producing well, an experimental well, an exploratory well, or the like. A well may be vertical, horizontal, or any angle between vertical and horizontal (a deviated well), for example a vertical well may comprise a non-vertical segment. A well may also be a multi-lateral well system.

As used herein, the term “pressure control assembly” refers to equipment which may include well control devices such as a wellhead, blowout preventer (BOP), a christmas tree, pressure control systems that may be attached to or incorporated in the wellhead BOP or christmas tree. While drilling a well, a pressure control is typically provided by a blowout preventer (BOP) which is installed on a wellhead. Once the well has been drilled, a completion is placed in the well that provides an interface with the subterranean formations and the tubular conduit for the well fluid and pressure control is provided by a christmas tree which is installed on top of the wellhead, and has isolation valves and choke equipment to control the flow of well fluids during production. The pressure control assembly may include control systems to monitor, measure, and react to sensor outputs from sensors at the well surface or down the well. The pressure control assembly may control one or more downhole safety valves. The pressure control assembly can perform functions including: allowing well drilling and well completion operations to be carried out under formation pressure; controlling the flow of fluids into or out of the well, including shutting off the flow; effecting a rapid shutdown of fluid flows commonly known as blow out prevention; and controlling hydrocarbon production operations.

As used herein, the term “well control” refers to the broad range of flow control measures that are taken to redirect the movement of pressure and fluids within a well.

As used herein, the term “wellhead” refers generally to the equipment that provides the structural and pressure containing interface for well drilling and production equipment. The primary purpose of a wellhead is to provide the suspension point and pressure seals for the casing strings that run from the bottom of the well to the surface pressure control equipment. A wellhead is typically installed during drilling operations and form an integral structure of the well. For offshore wells, the wellhead is typically referred to as a subsea wellhead.

As used herein, the term “christmas tree”, or “tree”, refers to any collection of valves, spools, and fittings used for an oil well, gas well, water injection well, water disposal well, gas injection well, condensate well, disposal well, and other types of wells. The primary function of a tree is to control the fluid flow into or out of the well, usually oil or gas. A tree often provides numerous additional functions including chemical injection points, well intervention means, pressure relief means (such as annulus vent), tree and well monitoring points (such as pressure, temperature, corrosion, erosion, sand detection, flow rate, flow composition, valve and choke position feedback, connection points for assemblies such as down hole pressure and temperature transducer (DHPT). Subsea wells and thus trees usually flow through flowlines to a fixed or floating production platform or to a storage vessel (known as a floating storage offloading vessel (FSO), or floating processing unit (FPU), or floating production and offloading vessel or FPSO or other combination of structures).

As used herein, the term “subsea well” means a well that has a wellhead proximate to the marine body bottom, such as an ocean bottom.

As used herein, the term “subsea” is intended to incorporate any body of water (fresh or salt water or otherwise). “Seafloor” and “surface of the sea” as used herein are intended to refer to the lower and upper surfaces respectively, of any body of water (fresh or salt water or otherwise).

As used herein, the terms “BOP” or “blow out preventer” refers to equipment generally used to control pressures in the annular space between the openhole and tubulars and equipment run in the well during drilling, completion, and workover operations.

As used herein, the term “multi-lateral well system” refers to a well having two or more independent laterals and share an hydraulic pathway. A multi-lateral well system has a primary pathway that extends from a wellhead down into a surface earth formation and at least one branch pathway that intersects the primary pathway at a subsurface location. A lateral may also extend from another lateral pathway. The creation of multi-lateral wells from either new or existing wellbores usually involves some sort of sidetracking process that utilizes whipstocks and/or section mills to create an exit point in the casing to allow a drilling assembly to “kick-off” from the main wellbore.

As used herein, the term “multi-entry well” refers to a well system having two or more independent wellhead or tree valve systems at or near the surface that share a hydraulic pathway.

As used herein, the term “multi-access well” refers to a well system having two or more pathways and may include aspects of either multi-entry and multi-lateral wells.

A multi-access well provides multiple pathways of access, either to subterranean formations, to surface, or both.

As used herein the terms “subterranean formation” and/or “subsurface formation” means a subsurface region, regardless of size, comprising an aggregation of subsurface sedimentary, metamorphic, and/or igneous matter, whether consolidated or unconsolidated, and other subsurface matter, whether in a solid, semi-solid, liquid, and/or gaseous state, related to the geological development of the subsurface region. A formation may contain numerous geologic strata of different ages, textures, and mineralogic compositions. A subterranean formation may include a subterranean, or subsurface, reservoir that includes oil or other gaseous or liquid hydrocarbons, water, or other fluids. A subterranean formation may include, but not limited to geothermal reservoirs, petroleum reservoirs, sequestering reservoirs, and the like.

As used herein, the term “well surface” when used with respect to a subsea well refers to the well at or near the seafloor.

DETAILED DESCRIPTION

The present invention relates generally to the design, construction and operation of wells in subterranean formations. A new well architecture is described herein that provides multiple “points-of-entry” (“multi-entry” wells) to achieve “multiple pathways”, thereby permitting multiple “means-of-access” (“multi-access” wells) to subterranean formations. The invention is particularly beneficial for applications having seasonal or operational constraints, emergency deployment considerations, environmental impact issues or economic drivers. The description of the invention disclosed herein, and its preferred embodiments, are not intended to limit the scope. Several modifications, alternatives and equivalents may be employed without departing from the scope and spirit of the invention.

FIG. 1 schematically illustrates one embodiment. Wellbore 10 is shown having been drilled from a sea floor 11. A well control assembly 12 is attached to the wellbore 10 at or near the mudline 11. Well control assembly 12 may comprise wellhead 14 and well control system 16 such as a christmas tree or BOP. A horizontal tubular 18 connects well control assembly 12 to a second well control assembly 20. Well control assembly 20 may comprise a wellhead 22 and well control system 24. The well control assembly 20 preferably provides substantially the same well control functionality on wellbore 10 as provided by well control assembly 12. A second horizontal tubular 26 extends from well control assembly 20 and brought to a vertical direction (not shown) to a floating vessel, a gravity-based platform, or to an onshore location. Any number of valves (not shown) may be utilized to regulate pressure and flow in horizontal tubulars 18 and 26.

Casing string 25 may be installed to support the weight and loads of the well control assembly 20 or to pre-configure another pathway entry point.

During drilling of wellbore 10 from a vessel, such as drill ship, a floating rig, a land-based rig, a shallow-water platform, a barge, an island, or substantially other location suitable to support such activity, a riser (not shown) is attached to the well control assembly 12 and drill string (not shown) is passed through the riser, through the well control assembly 12 into the wellbore for carrying out drilling operations. During such drilling operations, well control is carried out principally by well control assembly 12. In the event the functionality of well control assembly 12 becomes impaired or inoperative, some well control operations on wellbore 10 can be carried out using well control assembly 20. Well control assembly 12 may be configured to enable drilling to be carried out from a from a rig on a vessel (such as drill ship or a floating rig), a land-based rig, a rig on a shallow-water platform, or substantially any location suitable to support such activity. Similarly, well control assembly 20 may be configured to enable drilling to be carried out from a from a rig on a vessel (such as drill ship or a floating rig), a land-based rig, a rig on a shallow-water platform, or substantially any location suitable to support such activity.

FIGS. 2A, 2B, 2C, 2D, 2E, 2F, 2G, 2H, 2I, 2J, and 2K schematically illustrate additional embodiments of multi-entry well architectures in the practice of the present invention. The additional points of well entry shown in these figures may be implemented either concurrent or subsequent to other well construction processes, depending on the particular business need. In all cases, at least one pathway is at or near the surface between the multiple points of well entry.

In each of the FIGS. 2A through 2K, intercept wells are shown drilled from well control assembly 20. The intercept wells being well 28 a in FIG. 2A, well 28 b in FIG. 2B, well 28 c in FIG. 2C, well 28 d in FIG. 2D, well 28 e in FIG. 2E, well 28 f in FIG. 2F, well 28 g in FIG. 2G, well 28 h in FIG. 2H, well 28 i in FIG. 21, well 28 j in FIG. 2J, and well 28 k in FIG. 2K.

In FIG. 2A, well 28 a intersects wellbore 10 to provide a pathway juncture.

In FIG. 2B, well 28 b is drilled before wellbore 10 is drilled or at the same time wellbore 10 is drilled. Preferably, well 28 a before wellbore 10 is drilled to a depth in which it may encounter high pressures. In this embodiment, well 28 b is drilled to a location close to but not intersecting the wellbore. The lower end of well 28 b may be a few meters from wellbore 10 up to 100 or more meters. In the event well control assembly 12 is not adequate to control well 10 and well control assembly 20 is not adequate to control wellbore 10 through horizontal tubular 18, well 28 a may be drilled to intercept wellbore 10 to provide well control operations on wellbore 10. In the unlikely event well 28 b encounters a well control problem and can't be brought under control by well control assembly 20, wellbore 10 may be used as a relief well to assist in providing well control operations on well 28 b.

Intercept well 28 c in FIG. 2C, 28 d in FIG. 2D, 28 e in FIG. 2E, 28 f in FIG. 2F, and 28 g in FIG. 2G illustrate optional path configurations in which the intercept wells directly intercept wellbore 10.

Intercept well 28 h in FIG. 2H, 28 i in FIG. 2I, 28 j in FIG. 2J, 28 k in FIG. 2K have multi-lateral wells systems. In FIG. 2H, multi-lateral wells 29 a, 29 b, and 29 c are drilled from well 28 h to intercept wellbore 10. In FIG. 21, multi-lateral wells 30 a and 30 b are drilled from well 28 i to intercept wellbore 10. In FIG. 2J, multi-lateral wells 31 a, 31 b, and 31 c are drilled from well 28 j to intercept wellbore 10. In FIG. 2K, multi-lateral wells 32 a and 32 b are drilled from well 28 k to intercept wellbore 10.

FIG. 3 shows a multi-access well system similar to FIG. 2B except that wellbore 10 is illustrated having multi-lateral pathways, for example pathways 10 a, 10 b and 10 c. In the event well control operations are needed in pathway 10 c, pathway 328 may be drilled to intercept pathway 10 c to provide fluid communication for carrying out well control operations, such as plugging pathway 10 a.

FIG. 4 show multi-access well system similar to FIG. 2B except that a well template 13 provide support structure for three wells 10 d, 10 e, and 10 f, with well control assemblies 12 a, 12 b, and 12 c, respectively. Horizontal tubular 18 may be connected to a manifold that provides independent flow access to wells 10 d, 10 e, and 10 f. Flow path 428 may have been drilled to a location proximate wells 10 d, 10 e, and 10 f as shown as indicated by the solid line. Dashed line 428 a shows the path of pathway 428 in the event pathway 428 is extended to intercept one of the lines 10 d, 10 e, or 10 f. In FIG. 4, dashed line 428 is shown intercepting well 10 e.

The horizontal tubulars 18 and 26 may be assembled onshore and towed to the location or installed using a pipeline installation barge or other pipeline installation techniques well known in industry. A horizontal tubular is a tubular structure that is oriented primarily or substantially in a horizontal direction and that may arc vertical or bend at an intermediate angle at each end, and/or along the length of the tubular.

In some embodiments, well control assemblies 12 and 20 and horizontal tubulars 18 and 26 may optionally be buried below the seafloor to minimize potential ice flow impact on such structures.

The distance between well control assemblies 12 and 20 may be selected by persons skilled in the art taking into account the depth of wellbore 10, and water depth. For example, if blowout occurs in wellbore 10 and intercept operations from a floating drilling rig to complete drilling of well 28 b in FIG. 2B, the distance between well control assembly 20 and well control assembly 12 should be sufficient to ensure safe drilling activities in well 28 b.

Although only two well control assemblies 12 and 20 are shown in the drawings, the present method and system is not limited to two well control assemblies. Additional well control assemblies could be tied to the wellbore 12 to provide additional well-entry paths to wellbore 10.

Referring to FIG. 1, fluid communication access to wellbore 10 may be provided by the following paths:

(a) horizontal tubular 26, through well control assembly 20, through horizontal tubular 18, and through well control assembly 12 to wellbore 10; (b) vertical access (not shown in the drawing) to well control assembly 12 through well control assembly 12 to wellbore 10; and (c) vertical access (not shown in the drawing) to well control assembly 20, through well tubular 18, and through well control assembly 12 to wellbore 10.

The following functions, either along or in combination, can be carried out using the multi-entry well system of the present invention:

Data Access—The multi-entry well system permits obtaining data (e.g., pressure, temperature, acoustic, electromagnetic, strain, nuclear, passive seismic, etc.) along the access-entry pathway, at or near the point of pathway intersections, and along any other pathway segment comprising the well architecture and nearby surrounding subterranean formations. Flow Access—The multi-entry well system permits the movement of fluids (e.g., liquids, gases, chemical agents), particulate solids (e.g., gravel, proppant, salts, ball sealers), and small pumpable equipment (e.g., plugs, pigs, etc.). Mechanical Access—The multi-entry well system permits the use of mechanical conveyance (e.g., wireline, coiled tubing, jointed pipe, etc.) to run and position tools (e.g., bits, mills, scrappers, logs, etc.) and production equipment (e.g., packers, plugs, tubulars, hangers, etc.).

The technologies for creating junctures themselves may be adapted by persons skilled in the art using technologies for multi-lateral wells by modifying and inverting such tools as retrievable whipstocks and packers to aid in casing entry (i.e., rather than conventional casing exit) operations.

Referring to FIG. 2A and 2C through 2K, the following are non-limiting examples of applications of multi-entry wells:

Seasonal or Operational Constraints—Arctic drilling, completing, and production under ice: Well control assembly 12 (located offshore on the seafloor), which may be designated well entry access #1, may be configured for initial drilling and running of larger diameter casing strings, while well control assembly 20 (located onshore), which may be designated well entry access #2, may be configured for the remainder of the drilling and completions operations. Well control assembly 20 may also be used for subsequent production and minor well servicing operations while well control assembly 12 may be retained to facilitate major well servicing operations (including rapid well killing) and well abandonment operations at a later date. Emergency Deployment Considerations—Rapid response to a deepwater “blowout”: Well control assembly 12 (located offshore on the seafloor) may be configured for one of several wells planned to be drilled during a floating drilling operation through a subsea wellhead template (e.g., containing 2 to 20 wells slots). Referring to FIG. 4, well control assembly 20 (located offshore on the seafloor)—remotely positioned from the subsea template) might be pre-configured as a well control “relief” well for any of the subsea template wells and equipped for an immediate “top kill” operation or partially drilled to depth to permit either an intermediate-depth or deep “kill well” drilling operation. Environmental Impact Issues—Minimize production “footprint” after drilling: Well control assembly 12 (located onshore and positioned optimal to reach the reservoir) might be configured to be drilled, fracture stimulated, completed, and temporarily capped (i.e., no production tree), leaving no little or visible surface footprint until ready to be abandoned. Well control assembly 20 (located onshore and positioned for an obstructed view) might be configured to produce, log, and perform minor well servicing. Economic Value Tradeoffs Governing Risk/Cost/Benefit—Acquire data less expensively in subsea wells.

Well control assembly 12 (located offshore on the seafloor) may be configured to be drilled, completed, and produced. Well control assembly 20 (located offshore on a gravity based platform) may be configured to log, perform minor well servicing, and assist in well abandonment using pumpdown (i.e., pipeline “pig” like) tools.

It should be understood that the preceding is merely a detailed description of specific embodiments of this invention and that numerous changes, modifications, and alternatives to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the scope of the invention. Rather, the scope of the invention is to be determined only by the appended claims and their equivalents. 

1. A well comprising a first well control assembly directly associated with the well and a second well control assembly remotely and capable of being in fluid communication with the well.
 2. A subsea well system comprising two or more independent pressure control assemblies on or near the seafloor.
 3. The offshore well system of claim 1 wherein the well control assemblies are spaced apart by at least 200 meters.
 4. The offshore well system of claim 1 wherein at least one well control assembly is a blowout preventer.
 5. The offshore well system of claim 1 wherein at least one well control assembly is a christmas tree.
 6. The offshore well system of claim 1 wherein each well control assembly is connected to a wellhead.
 7. A method of providing multiple means of entry to a well connecting the surface with subterranean formations comprising: carrying out operations for drilling., completing, producing, servicing, or logging data; and utilizing multiple independent well control assemblies associated with the well, each well control assemblies having at least one well entry pathway substantially at or near the well surface. 